1. Field of the Invention
The present invention relates generally to registering a plurality of thin sheets of material, transporting them while registered through a processing station, and separating the sheets from each other. The invention more particularly relates to registering a copy sheet and an original sheet of film on a copyboard for transporting the film through an exposure station of a photographic duplicator and separating the copy film from the copyboard while leaving the original thereon.
2. Description of the Prior Art
As a result of the growing volume of documentary material presently being stored in photographic form, the need has arisen for a versatile photographic copier, and particularly a microfiche copier, which is both simple in design and operation, requires minimal operation maintenance, and has the capability of providing high quality single or multiple copies automatically.
A number of approaches have been taken in the past in an effort to meet this need and generally have proven satisfactory for their intended purpose. A typical microfiche duplicator is of the direct contact exposure type where a copy sheet, in contact with an original sheet, is exposed to actinic radiation (e.g., ultraviolet light) through the original and then developed. In such an apparatus, the original microfiche sheet and the copy film sheet are typically fed to the exposure station of the apparatus together in order that they may be held in direct contact and exposed while so contacted. Alternatively, if separate feeding devices are employed for the original and microfiche sheets, means must be provided for assuring that the two sheets become superposed at the exposure station and are in contact with each other during exposure.
Some of the prior art microfiche duplicators employ exposing apparatus which comprises a radiation-transparent cylinder, or at least a portion of which is radiation-transparent, around which the superposed original and copy sheets are fed. The sheets are normally maintained in contact with the periphery of the exposure cylinder by means of, for example, resilient and flexible conveyor belts.
Another approach of the prior art has been to dispose a radiation-transmissive flat plate above or opposite a source of radiation, such as an ultraviolet lamp, and feed the superposed sheets past the radiation-transmissive plate for exposure, the feeding being accomplished by means of, for example, a resilient roll which functions both to feed the superposed sheets past the exposure lamp and to maintain good contact between the two sheets during exposure.
Various means are also suggested in the prior art for feeding the original and copy sheets to the exposure device, such as endless belt means or other guide means through which are fed the two sheets to the exposure station. There has been a need for apparatus for feeding the original and copy sheets to the exposure device which is efficient in operation and which is not complex in design and which accurately registers the sheets together. The problem is further complicated by the fact that, in a direct contact type of microfiche duplicator, the original and copy sheets must be separated from each other after exposure so that the exposed copy sheet can be fed to the development means of the device. Therefore, the means for feeding the original and copy sheets to the exposure device must be designed so as to permit easy separation of the two sheets following exposure.
The problem of accurate registration of the copy with the original sheet has been recognized in the past, and the prior art has several suggestions for remedying this difficulty. For example, U.S. Pat. No. 3,211,073, Fosse et al, discloses an automatic apparatus designed to photographically reproduce film sections such as microfilm mounted in aperture cards. The patentees provide means for conveying the superimposed original and copy film sections in accurate registry past a photoprinter device. Referring to the figures of this patent, the superimposed cards are placed in a "pocket" 24 and proper longitudinal alignment thereof is assured by the fact that pusher members 58 move the cards into firm contact with an upstanding flange attached to a base plate. Proper transverse alignment is provided by an aligning assembly generally designated 171. Specifically, a spring mechanism serves to move a transversely reciprocatable head 185 engaging the ends of the cards to move the same in a direction transverse to the conveyor forcing the cards into firm contact with the inner faces of blocks 150 and 151. Following registration, a platen 155 presses the cards together and holds them so that there is no possibility for shifting of one card relative to the other as the individual pockets carrying the registered cards are conveyed across the exposure unit.
U.S. Pat. No. 2,927,210, O'Mara discloses a copying machine wherein superimposed original and copy sheets are fed to a standby position and longitudinally aligned by abutting a stop means which is upstanding on the frame supporting the device. Upon retraction of the stop means, the original and copy sheets begin the copying sequence and are fed through the exposure apparatus.
Several prior art patents disclose the use of electrostatic registration means; to wit, U.S. Pat. No. 3,650,623, Beispel; U.S. Pat. No. 3,661,457, Frech; and U.S. Pat. No. 3,676,001, Botkin.
Although not related to photocopying apparatus, U.S. Pat. No. 936,108, Ford discloses a feed mechanism adapted for use in feeding sheets of tin plate or other stiff material to a printing couple of a printing press and is provided with registering means to assure that the sheets are accurately positioned relative to the printing couple.
Thus, while the prior art suggests various techniques for assuring accurate registration of the original and copy sheets fed to the exposure station of a photocopying device, complex apparatus is often required. A need exists therefore for a sheet registration device which is simple in design and yet effective to assure accurate registry of a copy sheet with an original microfiche sheet prior to exposure in a photocopy device.
Of the above-described copy apparatus difficulties, one of the most significant is in the separation apparatus used to separate the master and copy sheets after exposing the copy through the master. In those devices which embody integral developing means with the exposing means, it is essential to separate the master and copy sheets after exposure and prior to development in order that the separated copy sheet can be fed to the developing part of the apparatus, and the master returned to the operator. If for some reason the master as well as the copy sheet is fed to the developing chamber, the master can be damaged significantly or, at worst, the information recorded thereon can be destroyed.
The prior art suggests various techniques for assuring positive separation of the master and copy sheets following exposure and prior to development. For example, many prior art devices utilize vacuum means to separate the master and copy sheets following exposure. This of course requires at least one vacuum-inducing device upon either side of the superposed original/copy sheets. A typical vacuum-separation means is disclosed in U.S. Pat. No. 3,549,255, Umahashi et al.
Another suggestion involves the use of a mechanical finger which catches the leading edge of the original which extends beyond the leading edge of the copy sheet thereby deflecting the original from the path leading to the development portion of the device. Reference is made to U.S. Pat. No. 3,419,328, Klosky et al and U.S. Pat. No. 3,416,863, Ralston for disclosure of such devices.
An alternative technique is disclosed in U.S. Pat. No. 3,215,055, Campbell et al, which relates to an automatic copying machine of the contact printing type. A carrier (having a pair of flexible magnetic strips disposed adjacent the edge portion beyond the outer edges of the original) bearing the original thereon travels around a transparent rotating drum in which is mounted a light source. A sheet of copy paper is superposed on the original and this superimposed assembly is then advanced between the drum and flexible guide means. Vacuum means is employed to separate the copy sheet from the original, and in order to prevent the separation of the original from the drum when multiple copies of the original are desired, magnetic means disposed within the transparent drum functions to hold the carrier (bearing the original thereon) in contact with the drum by acting with the magnetic means located in the carrier. In order to separate the carrier from the surface of the drum, a resilient ejector or deflector blade, actuated by a solenoid, contacts and resiliently biases the outer surface of the rotating drum thereby separating the original therefrom despite the attractive force exercised by the magnetic holding assembly. The continuing rotation of the drum moves the carrier assembly away from the outer surface of the drum and over the ejector blade which is pressed against the outer surface.
A related device is disclosed in U.S. Pat. No. 2,574,215, Kunstadter, which relates to an automatic-photo printing device wherein the superimposed original and copy sheets travel around a drum in which a light source is disposed. The leading edge of the original is behind the leading edge of the copy sheet as it travels around the drum. A separating tongue is kept against the surface of the drum and as the leading edge of the copy sheet reaches this point, it breaks an electromagnetic circuit and causes the tongue to be deflected against another cylinder which separates the copy sheet from the original and transports the copy sheet to the developing apparatus. The original remains on the first drum and is returned to the operator.
Simpler devices are suggested in the prior art, including mechanical fingers or claws which are disposed at a point intermediate the exposure station and the development station and are designed to "catch" or "trap" either the original or copy sheets and transport them either back to the operator or to the development section, respectively.
Reference is made to the following U.S. Patents which disclose other types of original/copy sheet separation apparatus: U.S. Pat. Nos. 3,022,716; 3,324,292; 3,331,276; 3,498,709; and 3,547,538.
Despite these teachings of the prior art, which ordinarily function as intended, the need exists for a simple yet effective sheet separation device for positively separating a copy sheet from an original sheet after the copy has been exposed through the original sheet thereby enabling the copy sheet to be fed to the development portion of the apparatus.